Distillation of tar



June 20, 1933. s. P. MILLER DISTILLATION OF TAR Filed June 7, 1927 4Sheets-Sheet 1 ATTORNEYS June 20, 1933. s P. MlLLER 1,915,251

DISTILLATION OF TAR Filed June '7, 1927 4 Sheets-Sheet 2 CMUEMSE/Z/OMOE/Vsf@ Figa- 7 8 (W In u j y A 6L 65. 66d@ 5 i M /5'0 22 /5 scm/@anaINV NTOR ATTORNEYS June 20, 1933. s. P. MILLER DISTILLATION OF TAR 4Sheets-Sheet 5 Filed June 7, 1927 ATTORNEYS .Fume 20, 1933. S P. MlLLER1,915,251

DISTILLATION OF TAR Filed June 7, 1927 4 Sheets-Sheet 4 '0/(5 ons-wwwf/@Y mmf/vsn Campi/VSE@ /20/ WA TER 1 ANI/"UNM ATTORNEYS Paienied June2o, 1933. 1,915,251

UNITED STATES PATENT OFFICE STUART PARMELEE MILLER, F TENAFLY, NEWJERSEY, ASSIGNOR T0 THE BARRETT COMPANY, 0F NEW YORK, N. Y., ACORPORATION OF NEW JERSEY DISTILLATION OF TAR This invention relates tocoke oven operacarbon content and fractionally condensing tion andparticularly to the utilization of the various products from this richgas. heat available in the gases produced at coke A Instead of coolingthe gases With amovens to distill coke-oven tar and to the promonialiquor or tar and throwing down heavy 5 duction of clean oil fractionsand pitches. condensates in the collector main and cross- 55 In theordinary operation of by-product over main With the ob]ect merely ofcooling coke-ovens the gases produced by the coking the gases, the heatof the hot gases may be operation pass from the individual ovensutilized according to this invention to vathrough uptake pipes andgoose-necks to a Aporize coke oven condensates and the gases Collectormain Common t0 the Ovens 0f the leaving the collector main are passedthrough 6o battery. The gases commonly known as a scrubber where theymay be scrubbed With foul`gases leave the ovens at high temaheavyhydrocarbon liquid, and the scrubbed perature7 e, g., 600 t0 700o C. 0rhigher enriched gases -are fractionated in any suitand carry aconsiderable proportion of volable fractionating device to thus recovernotatilized tare and Oils as Well as solid paronly the oils with whichthe gases have been 65 ticles of Coke, coal and carbon and otherenriched but also condensable oils originally impurities. Ordinarily,the gases are cooled present in the gases. as rapidly as possible by theapplication of Where several batteries are operated at one sprays ofammonia liquor or ammonia liquor plant, lordinarily only one batterywill be and tar in the goose-.necks and collector main, equipped tooperate according to the method 7o the heat in the gases being therebydissipated 0f nl y Invention, and this battery will be and lost. Therapid cooling causesseparation provided With fractionating means, and aof tar containing heavier oils in the collector scrubber may beprovlded. The tar products main. Further cooling is effected in thecrosspIOClllCed 1n the other batteries Will be conover main whichconnects the collector main eyed llOt to tblS 011e battery, and thereuti- 75 to the condensing system and an additional llZGd t0 I1I1Cl 1 thegaSeS Of'tbe OHG battery, quantity of tar carrying both heavier and andthese enriched gases will there be fraclighter oils is thus separated.The collected 'lOIla-dtar is ordinarily shipped from the coke ovenInstead 0f equlpping one Whole battery plant to a tar distillation plantfor distilla- Wlth means fOr el-lymg Out thlS lnventlOU, 80 tion andseparation of the oils and the proa Small number of the ovens of onebattery duction of pitches of varying qualities. I-Ianmay be eqlllppedWlt-b means fOr dlStllllng dling losses, freight charges anddistillation the tal PIOdUCed by the Other OVeIlS 0f the costs,including uel and capital and mainbattery and these tel Products may beCOU- Or the Special equipment veyed to the equipment of the small numbertenance expenses f required for distillation add to the costof et OvensWhere they may be CllStllled and the production of the tar distillationproducts. enriched gases sc t'ulebed and fractionated In the past, ithas been proposed to frac In a .battery consisting of sixty ovens, thetionate the Coke Oven gases directly by re heat in the gases from threeto ive ovens 1s covering condensable constituents of the cokelligclntthegfginhftrgiuiiiyrggdn t oven gases in stepwise condensers orcoolers. Ovens- B e in foul. Ovens for exarm All attempts at Such dlreettmctlonatloni ple,With stdpaliiite gshort collector main to however,appear t0 have been unsetsteetefy which scrubbing means and avfractionating 45 1n a eemmefelel Wayi system are connected, andoperating the re- 95 It 1S the Obleet 0f this lnventlon t0 PTO* mainingty-six ovens on the usual collecvide apparatus and a process forractionally tor main and condensing means, the tar prodl condensingcondensable constituents from ucts recovered from these fifty-six ovensmay coke oven gases. The invention comprises be distilled in thescrubber or in the collec- 50 obtaining a gas of high condensablehydrotor main or in an uptake still or simultaneously at two or more ofthese places in the separate small system. The gases thus enriched maybe successfully fractionated for recovery of oil fractions.

According to the preferred method of operation, the tar collected fromthe fty-six ovens is conveyed while still hot to the scrubbing devicewhich isconnected to, and receives the hot gases from, the shortcollector main communicating with the four ovens. The light constituentsof the tar are volatilized in the scrubber and the residue from thescrubber may be conveyed to distilling means, e. g., in the uptake pipeor collector main connected to the four ovens where it will be furtherdistilled and pitch is produced. By cooling the gases leaving thescrubber in scrubbing towers or in a bubble cap fractionating tower orin any other sultable fractionating and cooling means marketably purefractions' are recovered.

The ases leaving the coke oven contain a consi erable percentage ofdust, free carbon, coke braize, and possibly other insoluble materialswhich contaminate the products recovered direct from coke oven gases bythe usual practice. By enriching the gases with coal tar products fromthe other ovens, the ratio of insoluble impurities to the totalcondensable oils in the gases is much lower than the corresponding ratioin the unenriched gases. The scrubbing operationlowers the content ofthe solid impurities still further by removing a considerable proportionof the insoluble materials from the gas stream. In addition to entrainedsolid particles carried along by the gas stream according to the usualpractice, there is a mist of line tar particles, tar fog, which is alsocarried over. into the condensing apparatus and which contaminates theproducts there recovered. By enriching the coke oven gases as describedabove, the percent of tar fog based on condensable oils in the gases islowered considerably below the corresponding percent for unenriched gas.The scrubbing operation tends to lower the percentage of tar fog in therecovered products still further. It is therefore apparent that, as aresult of the combined enriching and scrubhing operations, purerproducts may be recovered than is possible without enriching the gasesor without scrubbing them. Furthermore, sharper -fractions may berecovered from enriched than from unenriched gases.

By equipping only a small proportion of the ovens with scrubbing andfractionating means and by volatilizing the tar products from otherovens in the gases from the ovens so equipped, the gases passing throughthe fractionating system are greatly enriched. By the proceduredescribed, the hydrocarbon content of the gases may be increased fromthe usual percent, i. e., approximately .percent or higher.

tilized, only one percent, to as much as twelve or fifteen By theenrichment of the gases with condensable constituents, thc directfractional recovery of condensable constituents from coke oven gases ismade commerciall practical. When fractionating enrichedy gases it isnecessary to handle in the fractionating system only a small fraction ofthe gases which it would be necessary to handle in order to recover thesame quantity of tar and oil products from unenriched gases, since thegases which are handled contain a much higher percentage of condensableproducts. l

By volatilizing the tar products recovered from most of the ovens of thebattery in gases from only a few of the ovens, the quantity of gaseswhich it is necessary to treat is far less than what would be necessaryin the case of gases from an entire battery of ovens. For example, intreating the gases from four ovens it is necessary to handle onlyone-fifteenth the quantity of gases which it would be necessary tohandle in treating the gases from a battery of sixty ovens, and whereasthe equipment necessary to handle sixty ovens would be large, expensiveand unwieldly and hence impractical, the treatment of' gases from butfour ovens is not a difficult operation from an engineering standpoint,and is distinctly practical from the investment and viewpoints. Theoperation may be carried out by distilling all or only cert-ainfractions of the products recovered in the collector main and condensingsystem of the fifty-six ovens in the example above, with the hot gasesfrom the four ovens. The treatment will be governed by the nature of theproducts which it is desired to recover. If lighter oils are desired,only lighter fractions may be treated, whereas if it is desired torecover a larger quantity of the heavy oils, only heavier products needbe distilled in the hot gases of the smaller number of ovens.

Instead of introducing the tar products from the other ovens into thescrubber only, where they are either entirely or partly volaa part ofthe products may be introduced into the scrubber and the balanceintroduced directly into the hot gases passing through the uptake pipesor collector main, where the lighter constituents are volatilized andthe gases thereby enriched. Likewise, the residue from the scrubber mayin whole orin part be transferred to distillation means in connectionwith the hot gases for further distillation and enrichment of the gasesin heavy oils. It is possible to first introduce all the tar intodistilling means in connection with the uptake pipes or collector mainand to scrub the gases with the pitch thus produced, but inasmuch as thehigher temperatures prevail in that part of the apparatus nearer theovens, it is advisable to operating operate in a counter-current mannerand first treat the products in the scrubber which is located away fromthe oven andthen treat the residue from the scrubber in the collectormain or the distilling means in connection with the uptake pipe.

Instead of introducing the tar to one scrubber and leading the residueto distilling means in connection with the hot gases of the oven, thetar may be circulated through several scrubbers countercurrent to thestream of the hot gases and the production of several grades of pitchmay be accomplished in this way. A

Enrichment of the gases may result from distillation at the scrubber`where a scrubber is used` or at any stage of the operation prior to thefractionation, such as, for example, in the uptake pipes or in thecollector main. Any appropriate manner of bringing a large surface ofthe tar products to be distilled into intimate Contact with the hotgases may he utilized. Countercurrent contact may be effected. .as byspraying the tar products into the uptake pipe. in a manner described indetail below; or the hot gases may be brought into intimate contact withlarge surfaces of the tar products at successive stages in the passageof the hot gases through the collector main. or other part of the systemprior to the scrubber. Such intimate contact may be attained by sprayingtar products into the collector main cr by agitating the stream of tarproducts flowing through the collector main to the required degree.

The required agitation can be accomplished by the use of a rotatingshaft running lengthwisc of the main or a number of such shafts runningacross the main with suitable paddles thereon or by vertical shafts withsimilar paddles. Rotating cones or other agitating and splashing devicesmay be disposed in the collector main and arranged to be actuated forthe purpose of throwing tar into the stream of gases and upon theexposed surfaces of the main. Discs, plates or spines on rotating shaftswill achieve the same purpose. The required agitation can also beaccomplished by the introductiongof compressed gases such, for example,as fuel or coke oven gases or steam through a suitable distributor pipeimmersed in the tar or suction Ts (McDanieltype ejectors) may be locatedin the main with their suction ends beneath the level of the tartherein. If the nozzles of the ejectors are allowed to extend above thesurface of the tar, a -spray of tar will be thrown into the gas. 1f thenozzles are allowed to remain below the level of the tar or pitch in themain, the tar will be circulated but will not to any extent be throwninto the gases. The efect of one or more of the mechanical agit-atingdevices mentioned may be augmented by the provision of suitable spraynozzles in the collector main and goose-neck through which tar may besprayed into the stream of gases iowing through the main.

The quantity of tar products brought into contact with the hot gasesshould be so regulated that the gases entering the scrubber will be atthe desired temperature. It may be desirable to introduce water orammonia liquor with the tar products which are sprayed or otherwiseintroduced into the uptake pipes or collector main. The regulation ofthe cooling effect can be accomplished more readily with water becauseof the higher specific and latent heats of water as compared with tarand oils. Itis possible therefore to add water and ammonia liquor in theproportion required to remove all heat eX- cept that needed for thedistillation of the tar products, and this may be varied depending uponthe type of product distilled, whether it be a high boiling or lowboiling product. and also upon the type of residue of unvolatilizedproducts which it is desired to obtain. l/Vhen hard pitch is desired asa residue. and high boiling products are distilled, less water can beadded, or no water at all.

The operation of the invention is illus` trated in a general way in theaccompanying drawings although the. invention is not limited to thedisclosure there given, but is to be interpreted broadly ineonnection'with all coke oven operations.

In the drawings,

Fig. 1 is a plan view of a coke oven batteryshowing a separate shortcollector main;

Fig. 2 is an elevation showing the separate short collector main systemof Fig. 1;

Fig. 2a shows a cross-section of one type of collector main equippedwith agitating means;

Fig. 3 is an elevation partly in cross-section showing a modifiedseparate short collector main equipped with uptake stills; and

Fig. 4 shows a modified condenser system.

Fig. 1 shows a section of a battery of coke ovens 5, in which four ofthe coke ovens are connected to a short collector main 7 by means ofuptake pipes 6. The short collector main drains through pipe 9 into thestorage receptacle 13. The collector main and goosenecks are equippedwith sprays 14 and 15, which are fed by the pipe 22. The gases from theshort collector mainl are conducted through the pipe 30 to the scrubber31, from which they are led successively through the fractionatingdevices 32, 33, and 34. The I to the decanter 56. The cooler 53 drainsinto the decanter 57. The cross-over maln 52 drains into the decanter58. Each of the decanters 56, 57, 58 is adapted to deliver the separatedtar or tarry oil into the tank 59. Separate tanks may be provided forrecoverin" the individual fractions separately.

eans is provided for conveying tar products from the tank 59 or from theseparate tanks (not shown) to the scrubber 31, which comprises the pipe60 and pump 61. Outslde tars may also be supplied through line 62'. Theshort collector main 7 may be sprayed with tar products from the tank59, through the line 62 which connects with the sprays 14 and 15. Theproducts passing through lines 60 or 62 may be heated if desire-d bymeans of heat interchanger 67 and 67.

The scrubber 31 drains into the tank 23 from which the residue may bepumped by the pump through the line 22 into the sprays 14 and l5 asabove described, or the scrubber 31 may be elevated so that the residucows directly to the collector main 7. The residue from the scrubber mayalso be pumped through the pipe 21 to fluslrthe collector main. Thepitch in the collector main may be recirculated through the pipe 27 bymeans of the pump 28, and/or it may be drawn ofi` to storage 13. It mayalso be circulated through the sprays 14 and l5 through lines 27 and 63.Each of the fractionating devices 32, 33 and 34 may be equipped with aseparate circulating system whereby the fractions recovered in thescrubbers are drained to the tanks 41, 42 and 43, respectively, fromwhich they are recirculated by the pumps 44, 45 and 46 to sprays 47, 48and 49, respectively, in the tops of the fractionating devices. Thesprays 49 may be supplied with Water or ammonia liquor instead ofcondensate from the tank 43. The tanks 4l, 42 and 43 are equipped withdrawoffs for ammonia liquor. From the last fractionating device 34 thegases pass to exhauster 54.

Residue from the scrubber may be recirculated through the scrubber fromthe receiver 23 by the pump 68 through the line 69, or the scrubber maybe supplied by the pump 68 from the receiver 13 with heavy residue fromthe collector main, or with some of the heavy fraction collected in 41.Tar from outside sources may be introduced through The spraying mediumfor the scrubber may be supplied entirely from one or more of thesesources, or it may be a blend of con-v densate from tank 59 togetherwith one or more of the residues run ofl` into 13, 23 and 41 or it maybe the product from any of the decanters. According to one method ofoperation, the gases are enriched either in the uptake stills or theshort collector main, or both, with tar from the tank 59, and thescrubber is supplied by recirculating residue vers 64, 65, 66 and 67 areprovided for con-l trolling the temperatures of the various sprayingmediums.

eat is removed from the gases by the oil circulated throu h eachfractionating device. Part of the eat may be utilized in evaporatin thelower boiling components in the oil d in, part of it may be removed assensible heat used in raising the temperature of the oil fed in.

Fig. 2a shows a cross-section of a short co1- lector main equipped witha shaft 7l on which are paddles 72. -Instead of providing paddles tobring the tar in the bottom of the collector main into intimate contactwith the gases, the collector main may be equipped with rotating coneson perpendicular shafts, or with McDaniel Ts, or any other appropriatemeans for bringing the tar into intimate contact with the gases.

Fig. 3 shows a cross-section of a modified form of uptake pipe, whichmay be termed an uptake still, such as covered by the application ofGeorge E. Brandon, Serial No. 154,- 746. The coke oven is representedgraphically at 81 and has the usual outlet 82 for escape of the hot cokeoven gases. A modified uptake pipe is indicated at 83 and connects 100at its upper end with pipe 84 leading to the short collector main 7 Themodified uptake pipe has an enlarged casing portion 86 and an innerupwardly extending pipe 87 formin an annular space between them. A baile88 105 is located above the upper end of the pipe 87 and above this isarranged a spray head 90 connected with the pipe 90 for supplying theproduct to be distilled thereto. The outlet for the pitch or otherresidue formed in the uptake still is located at the bottom of theenlarged casing 86, this outlet being indicated in the form of pipes 91leading to the manifold or collector pipes 92. From these collectorpipes the pitch or residue is led to the pitch storage 92'.

The modified uptake pipe illustrated has a series of doors or openings94 to permit inspection and cleaning and an upper door 95 carrying thebaille 88. Overflow outlets 96 120 are also provided.

When enriching coke oven gases in an uptake still instead of in thecollector main, the tar residue from the scrubber or tar products fromthe condenser system in connection with the long collector main, orother product to be distilled, ,is conveyed through the pipe 90 andsprayed into the still through the nozzle 90', or more than onenozzlevma be provided if this is desirable. The volav tilizedconstituents pass over into the short collector main 7 and are conveyedfrom there by the cross-over main 30 to the scrubbing device andfractionating system. The short collector malin should be lushed toavoid ac cumulation of solid hard pitch. The flush ing material may beresidue. from the scrubber or other residue tar or condensate, and maysubsequently be sprayed into the uptake still through line 90 and spraynozzle 90.

When employing uptake stills to enrich the gases, a residue from thesestills is obtained in 'addition to the condensates and residues obtainedin connection with a system such as just described, in which the gasesare en-` riched by distillation Ain the collector main. This residue maybe drawn 0H to storage as a marketable product,.or it may be used toflush the collector main or sprayed into the scrubber. Distillation inthe uptake stills may supplement or supplant entirely or in partdistillation in the collector matin, and with minor adaptations such assuggested above the system shown in Figs. 1 and 2 may readily beconverted into a system in which enrichment of the gases is effected inuptake stills. i

Fig. 4 shows in elevation a modified type of fractionating system inamore or less d iagrammatic manner. The drawings provlde fordistillation in the short collector main', and except for the modifiedcondensing system the system corresponds to that shown in Figs. 1 and 2.By minor changes it may be readily adapted to provide for distillationin uptake stills. Instead of recirculating the liquor recovered in eachof the fractionating columns through the same column as provided inFigs. 1 and 2, 4 shows an arrangement for countercurrent flow of gas andspraying medium. Water may be sprayed into the last column 103 and thecondensed constituents withdrawn into the decanter 104. From here, thehydrocarbon condensates are drawn ofi' into the tank 105 and the ammonialiquor recovered may be recirculated through the pump 106 into the spraydevice of the scrubber 103, o-r it may be withdrawn to the ammonialiquor storage 107. The spray for 102 is supplied from the tank 105 bythe pump 108. Inturn,the condensates are drawn of from 102 to the tank109 and the spray for the scrubber 101 is supplied from this tank 109 bythe pump 110. Similarly, the condensates from 101 are Withdrawn to thetank 111 and from there the spray for the scrubber 100 is supplied bymeans of the pump 112. The gases in such a condensation system enter thesystem through the pipe 118 and leave through the pipe 114. Theoperations may be so regulated that no light constituents will remain inthe product which Ais drawn off Jfrom the scrubber 100 into the storagetank 115. Likewise, the composition of each of the oils recovered Iin105, 109 and 111 may be modified. This may be accomplished by regulationof the temperature of the gas leaving each of the units 108, 102, 101and 100. The temperature may be regulated by varying the amount,character or temperature of the scrubbing medium fed into 102, 101 and100-and the amount and temperature of the water or ammonia liquor fedinto 103. Heat interchangers 116, 117, 118 and 119 are provided forcontrolling the temperature of each oftl1e scrubbing mediums. Thus itwill be readily understood by those skilled in the art that veryflexible operation is provided for, and that the products recovered maybe varied widely while still under close control.

Variations of this countercurrent fractiona- `tion in any well knownmanner are possible within the scope of this invention. Although onelargescrubber 100 and threev smaller scrubbers are shown in thedrawings, it is to be understood that the size and number of condensingunits may be varied to suit conditions. Thc scrubber 100 may be operatedas one unit of the condensing system in which the spraying medium ispassed countercurrent to the gases, or the scrubbermay be sprayed withtar products recovered in the tank 59 supplied through pipe 120, or withtar from outside sources through line 120. Other methods'of operationinclude spraying the scrubber 100 with residue from the collector mainthrough the pipe 121 'and pump 122, or when uptake stills are used thepitch residue from these stills may be used as a scrubbing medium. Theresidue from the scrubber can be recirculated throughpipe 123 by pump124.

The invention comprises methods of operatinga coke oven by-productsystem whereby the by-products are recovered direct as salable products,and it comprises means for carrying out such methods. The invention hasbeen illustrated in connection with a short collector main attached tofour ovens which supply the heat for distilling byproducts recovered inthe other ovens of a battery, but it is to be understood that thelinvention is not limited by the drawings, but is of broad scope, andwhereas the drawings show a short collector main in connection with fourovens of a battery the same equipment may be applied on a larger scaleto an entire battery and the invention is applicable broadly to allmethods of recovering tar from a coke oven system and volatilizing it inthe hot gases of certain ovens and fractionally cooling the gases soenriched with scrubbing before ractionating when desired. The shortcollector main may be placed in a location different from that shown; itmay be alongside, or above the regular main, or the coke oven batterymay be constructed as usual with a collector main connecting with eachof the ovens and in addition a short co1- lector main connecting with asmall number enriched gases so as to recover clean oil fracof the ovensand located at the back of the tions therefrom,

and separately collecting coke oven, in which case separate uptakes forthe clean oil fractions.

the small number of ovens affected are provided, valves being providedto divert the gases to the short main or to the usual main, as desired.

The gases may be enriched by distilling crude condensates recovereddirectly from the gases, or tars from other sources may be distilled.They may be condensates with a wide boiling range such as a composite ofall the condensates thrown down during the cooling of the gases.Further, the gases may be enriched by bringing the hot gases intointimate contact with residue from the scrubber in uptake stills orinthe collector main. Uptake stills may be supplied with residue from thecollector main. Condensates may be used for enriching the gases soonafter their recovery, while they are still warm, thereby economizingheat.

Coke oven systems now in use may be readily converted to operateaccording to my invention.

I claim:

1. The process which comprises spraying tar into hot coal distillationgases in such a manner as to distill the tar and scrub the gases thusremoving from the gases entrained particles originally present thereinand to substantially enrich the gases in their content of condensableoil vapors, maintaining the gases throughout the tar distillation andscrubbing at such a temperature that they retain the major portion oftheir origi nal condensable oils, subsequently cooling the scrubbed andenriched gases to condense clan oils therefrom, and recovering the cleano1 s.

2. The process which' comprises spraying tar into hot coal distillationgases in such a manner as to distill the tar and scrub the gases thusremoving from the gases entrained particles originally present thereinand to enrich the gases to many times their original content ofcondensable oil vapors, maintaining the gases throughout the tardistillation and scrubbing at such a temperature that they retain themajor portion of their original condensable oils, subsequentlyfractionally cooling the scrubbed and enriched gases to condense cleanoils therefrom, and separately collecting the clean oils.

3. The process which comprises spraying tar into hot fresh coke ovengases in such a manner as to scrub the gases, thus removing suspendedparticles therefrom, and to enrich the gases to at least l2 per cent ofcondensable vapors, and maintaining the gases during lthe tardistillation and scrubbing at such a temperature that they retain themajor portion of their original condensable oils, then fractionallycooling the scrubbed and In testimony whereof I affix my signature.

STUART PARMELEE MILLER.

